PALEONTOLOGICAL RESOURCES MANAGEMENT,

ANZA-BORREGO DESERT STATE PARK

GEORGE T. JEFFERSON

Colorado Desert District Stout Research Center, Anza-Borrego Desert State Park

200 Palm Canyon Drive, Borrego Springs, CA, 92004

____________________

Abstract—Paleontologic resources in California State Parks, including both organic and mineralized remains in body or trace form, are protected, preserved, and developed for public enjoyment, interpretation, education, and scientific research. Paleontological resource management goals for Anza-Borrego Desert State Parkâ (ABDSP) are summarized as follows: (1) determine the geological, stratigraphic and geographical distribution of fossil localities and potentially fossiliferous sedimentary deposits within the ABDSP region; (2) ascertain/evaluate the significance of these resources; (3) adequately protect significant resources on site or conserve them through recovery, such that their inherent scientific and interpretive values are not degraded; (4) evaluate previous research and determine avenues of investigation needed to adequately understand, conserve and interpret the resources; (5) use the results of such research to improve management procedures and methods; (6) adequately manage and care for ABDSP paleontologic collections; (7) promote cooperative studies and management partnerships with other concerned agencies; and (8) perform and publish relevant scholarly paleontologic research.

Paleontological resources in ABDSP are widespread and exceedingly diverse, and hundreds of square miles of fossiliferous badlands terrain occur in ABDSP. Baseline GIS locality data about the distribution and concentration of these resources has been compiled from archived aerial photographs and field notes. These data, locality information derived from reconnaissance of unexplored areas, and data recovered during intensive surveys are used to direct subsequent field operations and to plan cyclic survey programs for the fossiliferous regions of the Park. A subset of these plotted data also are provided to patrol rangers for resource protection purposes. Fossils may have interpretive, historical or scientific significance. Significance must be evaluated in order to make proper decisions and take appropriate management actions which may include on site protection, recovery and conservation, and/or study and exhibition.

____________________

INTRODUCTION

Anza-Borrego Desert State Park (ABDSP) (Acronyms used throughout the text are listed in Table 1.) encompasses over 600,000 acres of eastern San Diego County. It is the largest state park and is one of seven park units administered by the Colorado Desert District (CDD) of the Department of Parks and Recreation (DPR). DPR is organized under the California State Resources Agency whose objective is to further the conservation of California's resources. General mandates related to geological features and paleontologic remains are found in the State Public Resources Code (Division 1, Chapter 1, Article 1; Division 5, Chapter 1, Article 1, 5019.53, and Division 5, Chapter 1.7, 5097.5). Specific directions concerning identification and protection of paleontological resources are also found in the DPR Operations Manual (Section 1831(4):40 and 41). The DPR adheres to the basic content of the American Association of Museums Code of Ethics for museum curators, and the CDD specifically follows the Society of Vertebrate Paleontology Statement of Ethics.

The oldest fossils from ABDSP are Ordovician in age, over 450 million years (myr) old. However, there is a major hiatus between these and the next youngest middle Miocene remains of about 15 to 12 myr old. The most significant andabundant fossils are those of late Miocene-Pliocene terrestrial vertebrates and marine organisms, which range in age from about 7 to 4 myr ago, and Pliocene-Pleistocene terrestrial vertebrates, which date from 4 to about 0.4 myr ago.

A variety of changing environments and habitats are represented, and over 500 types of fossil plants and animals have been reported. These range from preserved microscopic plant pollen and algal spores to baleen whale bones and mammoth skeletons (Tables 2-4). Combined with the long and complete regional geologic sequence in ABDSP, these ecologically diverse fossil assemblages are an unparalleled and highly significant paleontologic resource of international importance (Webb 1998). Both the Plio-Pleistocene Epoch and the Blancan-Irvingtonian North American Land Mammal Age (NALMA) boundaries fall within the terrestrial section. These strata also record terrestrial faunal interchange between Asia and North America (taxa like Lepus, Pliopotamys, Synaptomys, Mammuthus meridionalis, M. columbi, Cervidae, and Ovibovinae), and from South America to North America (taxa like Paramylodon, Nothrotheriops, Coendu, and Erethizon) (Webb and Barnosky 1989).

TABLE 1. Acronyms

ABDSP Anza-Borrego Desert State Park
AMNH American Museum of Natural History
BLM Bureau of Land Management
BSF Borrego San Felipe
CC Coyote Canyon
CDD Colorado Desert District
CM Coyote Mountain
DPR Department of Parks and Recreation
DSRC District Stout Research Center
GIS geographic information system
GPS ground positioning system
IF Imperial Formation
IVCM Imperial Valley College Museum
LACM Natural History Museum of Los Angeles Co.
PS Anza-Borrego Desert SP Paleotology Soc.
UCB University of California Berkeley
USGS US Geological Survey
VC Anza-Borrego Desert State park Visitor Center
VCFC Vallecito Creek-Fish Creek

GEOLOGIC SETTING

ABDSP lies in a unique geologic setting along the western margin of the Salton Trough. This major topographic depression forms the northernmost end of an active rift valley and continental plate boundary. The Trough extends north from the Sea of Cortez (Gulf of California) to San Gorgonio Pass, and from the eastern rim of the Peninsular Ranges east to the San Andreas Fault Zone. Over the past 9 to 10 myr, a relatively complete geologic section of over 6 km (20 k feet) of fossiliferous sediment has been deposited within ABDSP, along this rift valley's western margin.

The principal fossil-producing stratigraphic units include the Imperial Formation (IF) (Hanna 1926; Tarbet and Holman 1944; Keen and Bentson 1944; Dibblee 1954; Allen 1954; Stump 1972; Powell 1986; Remeika 1998b, 1991; also known as the Imperial Group, Remeika 1995; Winker and Kidwell 1996) and Palm Spring Formation (Woodring 1931; Tarbet and Holman 1944; Dibblee 1954; Cassiliano 1998, 1999) in the Vallecito/Fish Creek Basin (VCFC) and Coyote Mountains (CM) region, the Imperial, Palm Spring, and Ocotillo Conglomerate (Dibblee 1954; Ocotillo formation of Remeika 1992b) in the Borrego Badlands of the Borrego/San Felipe Basin (BSF), and the Bautista Formation (Frick 1921) in Coyote Canyon (CC).

The badlands exposures of these sediments cover over 160 square miles (102,400 acres) of ABDSP. Along the west side of the Salton Trough, some of these formations extend east and southeast from ABDSP, across Ocotillo Wells State Vehicular Recreation Area, and the Superstition Hills on Bureau of Land Management (BLM) property, reaching the Salton Sea. They also occur to the south in the CM and Yuha Desert, on BLM lands, and extend into Baja California del Norte, Mexico.

HISTORY AND RESEARCH

Although invertebrate fossils were reported from the Colorado Desert region in the mid-19th century (Conrad 1854, 1855; Schaeffer 1857), paleontologic investigations in what was to become ABDSP began in 1893 with the identification of fossil corals from the IF (Carrizo Creek beds) in the CM area by J. C. Merriam of the University of California, Berkeley (UCB) (Fairbanks 1893, Arnold 1904, 1906). Early in the 20th century, the invertebrate fauna from the IF, exposed in the VCFC, Alverson Canyon (also Fossil Canyon) south of CM, and BSF to the north, was the subject of investigations and numerous scientific papers by researchers with the California Academy of Sciences, California Division of Mines and Geology (then the California State Mining Bureau), California Institute of Technology, Stanford University, the UCB, University of California, Los Angeles, and the US Geological Survey (USGS) (Bowers 1901; Arnold 1904, 1906, 1909; Vaughan 1904, 1917a, 1917b; Mendenhall 1910; Kew 1914, 1920; Dickerson 1918; Hanna 1926; Hertlein and Jordan 1927).

Less attention was directed to the invertebrate fauna from the IF during the 1930's through 1950's (Grant and Gale 1931; Woodring 1931; Bramkamp 1935; Durham 1944, 1954; Tarbet and Holman 1944; Grant and Hertlein 1956; Christensen 1957), with an increase in investigations from the 1960's to the present. Researchers from ABDSP (Remeika and Fleming 1995), the University of California, Riverside (Jefferson 1966; Lasby 1969; Ballard 1971; Bauersfeld 1971; Douglas 1971; Morgan 1971; Mount 1974, 1988; Schremp 1981; Murphy 1986), the University of Chicago (Kidwell 1988; Kidwell et al. 1988), California State University, San Diego (Stump 1970, 1972; Stump and Stump 1972, Bell 1980; Pappajohn 1980; Dean 1988, 1996), the USGS (Powell 1987, 1995; Fleming 1993a, 1993b, 1994; Fleming and Remeika 1994; McDougal et al. 1994), and others (Durham and Allison 1961; Merriam and Bandy 1965; Dowlen 1969; Coble 1978; Crouch and Poag 1979; Foster 1979; Quinn and Cronin 1984; Watkins 1990a, 1990b; Tucker et al. 1994; Weinberg pers. comm. 1994) have continued work on invertebrates from the IF.

Vertebrate fossils were first found in ABDSP by C. Alverson and reported by Bowers (1901) 32 years before the Park was established. During the late 1930's, G. Hazen and party from the Frick Laboratory of the American Museum of Natural History (AMNH), New York, surveyed and collected in the BSF and the VCFC from 1936 through 1938. The California Institute of Technology recorded two localities in the Borrego Badlands during the mid-1930's.

During the Second World War, the Park was essentially closed and many areas were used for military exercises. Although H. Garbani discovered vertebrate fossils in the VCFC in 1940, paleontologic investigations and studies did not resume until the early mid-1950's, after he had contacted T. Downs of the Natural History Museum of Los Angeles County (LACM) (Garbani pers. comm. 1996).

H. Garbani is credited with drawing attention to the VCFC vertebrate paleontology resources and initiating the most productive phase of research in the region. This work was headed by staff and research associates of the LACM including T. Downs, L. Bessom, H. Garbani, H. Howard, G. Miller, J. White, and G. Woodard. The LACM and others continued active work focusing on the Palm Spring Formation in the VCFC through the 1980's (Downs 1957, 1965, 1966, 1967; Brattstrom 1961; Downs and Woodard 1961a, 1961b; White and Downs 1961, 1965; Howard 1963, 1972a, 1972b; White 1964, 1965, 1968, 1969, 1970, 1984, 1991; Downs and White 1965a, 1965b, 1966, 1968; Zakrezewski 1972; Becker and White 1981; Hutchison 1987; Jefferson 1989; Martin and Prince 1989; Norell 1989; Downs and Miller 1994).

In the early 1970's, G. Miller of Imperial Valley College, began an active and productive collection and curation program of ABDSP vertebrate fossils. Most of these collections were conserved at the Imperial Valley College Museum (IVCM), and were the subject of research and publications (Miller 1977a, 1977b, 1979, 1985a, 1985b; Miller et al. 1982, 1988, 1989, 1991; Parks et al. 1989; Downs and Miller 1994). Vertebrate fossils were also housed at the ABDSP Visitor Center (VC), which opened in 1979. In 1982, preparation of paleontologic materials largely shifted from the VC to the Stout Paleontology Laboratory at Park headquarters. With the death of G. Miller in 1989, paleontology projects at the IVCM were scaled down, and for the following several years, the program was supervised by J. White of the University of Arizona, Tucson and B. Stout of Anza-Borrego Desert Natural History Association and the Desert Research Institute, Reno, Nevada. Important graduate research on the vertebrate faunas were supervised by J. White, including Cunningham (1984), Cassiliano (1994), and Blackford (1995).

In 1991, ABDSP staff assembled a Paleontology Advisory Board consisting of paleontologists and museum professionals from institutions throughout the western US to provide recommendations and direction in the management of ABDSP paleontologic resources. At the suggestion of the Board, IVCM collections were transferred to ABDSP in 1992, and the LACM vertebrate collections, recovered under State permits from ABDSP, were transferred to ABDSP in 1997. G. Jefferson was hired as CDD Paleontologist in 1994.

Construction of the CDD Stout Research Center (DSRC), which houses a research library and conserves not only the above paleontologic collections but natural history, historic and archaeologic collections, was completed in 1999. The paleontological library holdings, with over 15,000 separates, is an important resource for management and research, and includes the combined collections of G. Jefferson, G. J. Miller, and John A. White. The DSRC facilitates a variety of museum and university research projects and cooperative resource management programs that are supported by both private and agency funds. The ABDSP Paleontology Society (PS) was formed in 1993 to assist CDD staff in managing paleontological resources and collections. Members of this volunteer group are trained to professional standards and State certified in field surveying, specimen preparation, and curation activities.

ABDSP/CDD staff and others have continued research and publication on ABDSP fossils (Remeika et al. 1986; Remeika and Fleming 1995; Remeika 1988, 1991, 1992b, 1997a, 1997b; Stout and Remeika 1991; Martin 1993; Remeika and Jefferson 1993; Stewart and Roeder 1993; Cassiliano 1994; Jefferson 1994, 1995a, 1995b, 1999a; Jefferson and Tejada-Flores 1995; Jefferson et al. 1995; McDonald et al. 1996; Murray and Jefferson 1996; Remeika and Beske-Dehl 1996; McDaniel and Jefferson 1997, 1999a, 1999b, 2000; Jass 1998; Campbell et al. 1999; Jolly 2000). The late Tertiary and Quaternary paleontology of ABDSP was recently summarized (Remeika et al. 1995; Remeika 1998b), and the taphonomy and biostratigraphy of the mammalian fossils from the VCFC recently described (Cassiliano 1997, 1998, 1999).

Figure 1. Specimen Protocols and Process
Specimen Protocols and Process

 

Figure 2. Systematic List of Fossil Plants from Anza-Borrego Desert State Park

Systematic List of Fossil Plants from Anza-Borrego Desert State Park

Systematic List of Fossil Plants from Anza-Borrego Desert State Park




PALEONTOLOGICAL RESOURCES

The oldest reported fossils from ABDSP area are conodonts of early Ordovician age, ca. 450 myr (Dockum and Miller 1982; Miller and Dockum 1983) (Table 4). These tooth-like structures from agnathan vertebrates occur in the marine metasediments east of Carrizo Mountain. Miller and Dockum (1983) correlate these deposits with those of the Santa Rosa Formation (also see Mueller and Condie 1964) in the Santa Rosa Mountains, north and northeast of Clark Dry Lake.

Cretaceous plant pollen, spores and dinoflagellates (Fleming 1993a, 1993b, 1994; Fleming and Remeika 1994; Remeika and Fleming 1994, 1995) (Table 2) are known from Pliocene formations in the VCFC. These microfossils have been eroded from Mesozoic age strata on the Colorado Plateau and transported by the ancestral Colorado River into the Salton Trough. Seven taxa of reworked Cretaceous foraminifera (Table 3) have been identified from the same units (Merriam and Bandy 1965). Also, reworked Eocene plant microfossils have been described from the VCFC (Fleming 1993a, 1993b, 1994; Fleming and Remeika 1994; Remeika and Fleming 1994, 1995).

A diverse variety of invertebrates has been recovered from the IF in the VCFC and CM (Hanna 1926; Douglas 1971; Stump 1970, 1972; Stump and Stump 1972; Powell 1984; Dean 1988, 1996; Mount 1988) (Table 2, 3). These organisms include calcareous nanoplankton and dinoflagellates (Dean 1988, 1996), plant pollen and spores (Dean 1988, 1996), foraminifera (Tarbet and Holman 1944; Durham and Allison 1961; Ingle 1974; Crough and Poag 1979; Quinn and Cronin 1984), sponges (Dowlen 1969), corals (Vaughan 1904, 1917a, 1917b; Dowlen 1969; Foster 1979), polychaeta (Dowlen 1969), bivalves (Arnold 1906; Dickerson 1918; Powell 1986, 1987), gastropods (Dickerson 1918; Powell 1986, 1987), echinoderms (Kew 1914, 1920; Grant and Hertlein 1956; Powell 1995), and crustaceans (Dowlen 1969; Quinn and Cronin 1984; Tucker et al. 1994) (Table 3). Many of these forms are related to Caribbean species, and represent a time several myr prior to the emergence of the Isthmus of Panama (Arnold 1904; Mount 1974; Foster 1979; Quinn and Cronin 1984; McDougal et al. 1994).

In many areas, marine invertebrate fossil remains are well preserved and abundant. Carbonate platform, outer and inner shelf, near shore and estuarine/brackish depositional marine environments are represented (Arnold 1909; Ingle1974; Coble 1978; Bell 1980; Bell-Countryman 1984; Quinn and Cronin 1984; Richardson 1984; Watkins 1990b). The latter is typified by thick channel deposits of predominately oyster and pecten shell coquina (Watkins 1990a).

The IF also yields fossil marine vertebrates (Mitchell 1961; Deméré 1993; Thomas and Barnes 1993). The taxa represented include sharks and rays, bony fish, baleen whale, walrus, and dugong (Table 4).

The Pliocene age, Carrizo Local Flora (Remeika et al. 1988; Remeika 1994; Remeika and Fleming 1995) includes a palm, a cupressid, and deciduous hardwoods (Table 2). Charaphytes are also known from the fresh water deposits of the Palm Spring Formation in the VCFC. Mid to late Pleistocene fossil woods also have been recovered from the Ocotillo Conglomerate and Bautista Formation in the BSF (Remeika pers. comm. 1996).



Table 3. Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region

Table 3 Continued
Systematic List of Fossil Invertebrates from the Anza-Borrego Desert State Park Region



Lacustrine and fluvial fresh water invertebrates (Table 3) have been recovered from the Borrego, Brawley (Tarbet and Holman 1944; Durham 1950; Dibblee 1954), and Bautista Formations (Frick 1921; Remeika pers. comm. 1996; Gensler pers. comm. 2001), in the BSF (Remeika pers. comm. 1996), and Palm Spring Formation, in the VCFC (Taylor 1966, pers. comm. 1976, 1977, 1982). The identified taxa include bivalves, gastropods, and ostracodes (Sohn pers. comm. 1961; Quinn and Cronin 1984; Steinmetz pers. comm. 1998) (Table 3).

The oldest terrestrial vertebrates within ABDSP are from the Borrego Buttes. The remains, which include a gomphothere or paleomastodon, pseudaelurine felid and small stilt-legged camelid (Table 3), were recovered from near shore lacustrine deposits (Jefferson 1999a). The strata are thought to correlate with the Split Mountain Formation (Woodard 1963, 1974; Kerr et al. 1979; Winker 1987; Cassiliano 1994) that occurs below the base of the Imperial Formation. They predate the Fish Creek Gypsum, and fall in a 12-9 myr age range (Dean 1988, 1996; Kerr and Abbott 1996; Jefferson 1999a).

The late Miocene through mid-Pleistocene Layer Cake, Arroyo Seco, and Vallecito Creek vertebrate assemblages occur in a superposed, conformable biochronologic sequence (see Remeika et al. 1995, and Cassiliano 1999). The Layer Cake assemblage (Hemphillian and early Blancan NALMA) falls within the Gilbert Magnetochron, and ranges between about 4.0 and 3.4 Ma. The Arroyo Seco assemblage (mid-Blancan NALMA) directly follows the Layer Cake assemblage at about 3.4 Ma. Volcanic ash fission track analyses (Johnson et al.1983) place the transition between the Arroyo Seco assemblage and the following Vallecito Creek assemblage before the end of the Gauss Magnetochron at 2.3 + 0.4 Ma. The Vallecito Creek assemblage (late Blancan through mid-Irvingtonian NALMA) falls within the Matuyama Magnetochron, and ranges from the base of the Matuyama to the Jaramillo Magnetosubchron, or from about 2.3 to 0.9 Ma. For a discussion of the VCFC faunal sequence and chronology, see Downs and White (1968), Johnson et al. (1975), Opdyke et al. (1974, 1979), Lindsay, et al. (1987), Lundelius, et al. (1987), Lindsay and White (1993), Remeika et al. (1995), and Cassiliano (1999).

The Borrego LF (Remeika and Jefferson 1993) (Irvingtonian NALMA) ranges in age from about 1.25 to as young or younger than 0.37 Ma (Remeika and Beske-Dehl 1996, 1998a). It overlaps chronologically with the upper range of the Vallecito Creek assemblage, and falls within the Matuyama and Brunhes Magnetochrons. The stratigraphic section also includes the Bishop Tuff, dated at about 0.76 Ma (Rymer 1991).

COLLECTIONS AND ARCHIVAL DATA

The CDD paleontology core collections consist of paleobiologic specimens acquired and conserved because of their scientific significance and educational value. Collections facility and curatorial standards are maintained in compliance with State Museum Collections Management Handbook (1998, 2000). Fossil plants, marine and fresh water invertebrates, and vertebrates are conserved at the DSRC. Each group, for example plants or vertebrates, is organized internally by local assemblages (= stratigraphic and/or geographic divisions), locality number, and specimen number (see Murray 1996). On-going paleontologic research and active resource management practices result in an annual increase of about 0.2 % in the number of prepared and catalogued specimens.

Primary specimen and locality data (up to 86 data fields) for the vertebrates presently reside in the State-wide Argus museum collections data system in Sacramento. It is directly accessed via telephone link from the DSRC. Botanic and invertebrate fossil data are maintained at the DSRC in Access. The DSRC also houses archival data that include original field notes, annotated topographic maps, aerial photographs and digital maps, both digital and standard photographs of sites and specimens, standard DSRC locality data sheets (in data base field format), specimen preparation records, original catalogue card files (IVCM) and digital catalogues (IVCM, LACM), research notes, correspondence, and reports and publications. Over 1,000 vertebrate specimens have been described in formal publications and/or gray literature.

Vertebrate paleontologic locality point data, previously recorded by ABDSP, IVCM and LACM on US Department of Agriculture (1953) aerial photographs were captured digitally as GIS point layers that include over 2.4 k localities. The points are annotated with institutional acronyms and locality numbers, permitting the linkage of locational or taxonomic information from any nested set of data fields within the database. These data can be combined with topographic contours, roads and trails, and/or digital orthoquadrangle shaded topography, and printed at any scale for field survey and reporting purposes. Locality data are considered highly sensitive proprietary information which are made available only to qualified researchers through a permit process.

Marine invertebrates recovered from the IF in the CM and VCFC, fresh water invertebrates from formations in the BSF and VCFC, and fossil woods from the BSF and VCFC comprise the core of the plant and invertebrate collections. Locality numbers for fossil invertebrate specimens recovered regionally from the IF that are housed at other institutions (California Academy of Sciences, San Francisco; California State University, San Diego; Imperial Valley Archaeological Museum, El Centro/Ocotillo; Milwaukee Public Museum, Wisconsin; LACM, Invertebrate Paleontology and Vertebrate Paleontology Sections; San Diego Museum of Natural History; San Diego State University; University of California, Berkeley, Museum of Paleontology; University of California, Los Angeles, Department of Geology; University of California, Riverside, Department of Geological Sciences; USGS) have been compiled as a research aid. Much of the material obtained by the above institutions was collected before ABDSP became a State Park.

The AMNH collection of fossil vertebrates was acquired prior to the use of State collecting permits. Also, portions of the BSF and VCFC were not part of the Park in 1936/1937.

Table 4. Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park
Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

 

Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

 

Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

 

Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

 

Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

 

Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

 

Systematic List of Fossil Vertebrates from Anza-Borrego Desert State Park

The materials collected by Hazen et al. are presently housed in the AMNH. Accessory data for most of these localities and specimens are archived also at the DSRC. The IVCM collection of fossil vertebrates was recovered from the BSF, CC and VCFC under a series of standard State permits (1970-1990). Over 7,000 specimens were collected and catalogued. Essentially the entire LACM collection of fossil vertebrates was recovered under State permits (1954-1985). Between 1954 and 1982, LACM staff and research associates recovered approximately 10,000 vertebrate specimens, primarily from the VCFC. Primary taxonomic holotypes have been retained by LACM, and are conserved within the Vertebrate Paleontology Section of that institution. In addition, the LACM presently houses California Institute of Technology specimens that were collected in the 1930's. A few vertebrate fossil specimens from the BSF are conserved by the Earth Sciences Section at the San Bernardino County Museum, Redlands.

MANAGEMENT ISSUES AND PRACTICES

Large parts of ABDSP have not been explored or surveyed for paleontologic remains (Jefferson 1999b). Many of these areas are remote, and human disturbance is presumed to be minimal. Nevertheless, paleontologic resources are also subject to rapid degradation through natural weathering processes. The significance of paleontologic resources, if any, in these unexplored territories will be assessed, and appropriate management plans formulated. Since 1993, the PS and CDD staff have been systematically intensively surveying (National Park Service 1977; Wylie 1991) specific areas within ABDSP, and significant fossil remains have been recovered. Baseline GIS locality data about the distribution and concentration of these resources is used to direct subsequent field operations and to plan cyclic surveys (Fremd 1995). Also, the condition of major vertebrate ichnite exposures is now annually photo-monitored and assessed.

The significance of paleontologic specimens must be evaluated in order to make proper decisions and take appropriate management actions (Fig 1). Fossils may have interpretive, historical, and/or scientific significance. While the former are relatively easy to determine, scientific significance may not be readily evident. For the purposes of intensive or cyclic paleontologic surveys at ABDSP, all vertebrate fossils taxonomically identifiable to the generic and in some cases to the Family or Ordinal level are considered scientifically significant. Hopefully, recovery of these specimens will allow future researchers to address biological guild level paleoecological issues.

However, no single criterion determines scientific significance, and some fossils may not be significant. Among the factors which make some specimens important are: represents poorly known taxa, preserves soft tissues or delicate structures, exhibits pathologies or injuries, unusual size or shape, reveals paleoecological relationships (such as symbiosis, parasitism, commensalism, predation), and/or are associated with datable stratigraphic horizons. However, many other subtle factors may make a specimen scientifically significant. Species that are abundantly represented may yield population-based data such as the degree of individual variation or sexual dimorphism (Remeika 1992a). Common taxa may record important geological and geographical range extensions, may be useful for regional geologic correlations, or provide information about depositional environments.

Management and protection of regionally distributed resources may require multi-agency cooperation. Recently, ABDSP and the BLM established an interagency agreement for the cooperative management of exposures of the IF in the CM area and Alverson Canyon, along the southern border of the Carrizo Impact Area of ABDSP (Remeika 1995). Here, the BLM lands have been designated an Area of Critical Environmental Concern because of the fossiliferous IF deposits.

As recreational land uses intensify, protection of paleontological resources from human actions, deliberate or unintentional becomes critical. Fortunately within ABDSP, poaching of specimens and vandalism of geological features has been minor. However, illegal trespass and damage by off-highway vehicular traffic has increased. Violations result in imprisonment and/or fines (punishment depends on the severity of the offence). Protective measures include route designations and access closures, signage and regular aerial and ground-based ranger patrols of sensitive areas. Rangers are made aware of the importance of resource protection and are provided with GIS generated maps for a variety of resources including fossils. Proactive measures include interpretive exhibits at the VC, park-wide AM radio information, public education pamphlets about fossils, and on site interpretive signage.

Fossils are a nonrenewable natural resource. If an organism has a fossil record, it is represented by a finite number of specimens, and that number decreases as fossils are destroyed by natural or human actions. Delimiting the geologic and geographic distribution of fossiliferous deposits, identification of the fossil materials, and evaluation of the significance of these paleontological resources are prerequisites to conscientious and responsible resource management. Promoting an understanding of these resources and their contribution to the biological prehistory of the California landscape is important to their protection and appreciation.

REFERENCES

A relatively complete bibliography on Salton Trough regional geologic and paleontologic topics has been complied by Jefferson et al. (1995). The abridged version below includes all citations that appear in this text and it has been updated with post-1995 publications.

Allen, C.R., 1954. Geology of the north side of San Gorgonio Pass, Riverside County. In Geology of Southern California, edited by R.H. Jahns, California Division of Mines Bulletin 170:map sheet 20.

Arnold, R.E., 1904. The faunal relations of the Carrizo Creek beds of California. Science 19:1-503.

—— 1906. The Tertiary and Quaternary pectens of California. U.S. Geological Survey Professional Paper 47:84-85.

—— 1909. Environment of the Tertiary faunas of the Pacific Coast of the United States. Journal of Geology 17:509-533.

Ballard, A., 1971. The paleoecology of a marine deposit in the northwest Indio Hills. Manuscript on File Department of Geological Sciences, University of California, Riverside 12 p.

Bauersfeld, A.G., 1971. Paleoecology of the Tertiary fauna, Willis Palms Formation, Thousand Palms quadrangle, California. Manuscript on File Department of Geological Sciences, University of California, Riverside 19 p.

Becker, J.J., and J.A. White, 1981. Late Cenozoic geomyids (Mammalia: Rodentia) from the Anza-Borrego Desert, southern California. Journal of Vertebrate Paleontology 1:211-218.

Bell, P.J., 1980. Environments of deposition, Pliocene Imperial Formation, southern Coyote Mountains, Imperial County, California. Master of Science Thesis, San Diego State University, California 72 p.

Bell-Countryman, P.J., 1984. Environments of deposition, Pliocene Imperial Formation, Coyote Mountains, southwest Salton Trough. In The Imperial Basin, Tectonics, Sedimentation and Thermal Aspects, edited by C.A. Rigsby, Society of Economic Paleontologists and Mineralogists 40:45-70.

Blackford, L.C., 1995. Postcranial skeletal analysis of the Pleistocene deer, Navahoceros fricki (Cervidae). Master of Science Thesis, Quaternary Studies, Northern Arizona University, Flagstaff 144p.

Bowers, S., 1901. Reconnaissance of the Colorado Desert Mining District. California State Mining Bureau 11:1-17.

Bramkamp, R.A., 1935. Stratigraphy and molluscan fauna of the Imperial Formation of San Gorgonio Pass, California. Doctoral Dissertation, University of California, Berkeley 371 p.

Brattstrom, B.H., 1961. Some new fossil tortoises from western North America with remarks on the zoogeography and paleoecology of tortoises. Journal of Paleontology 35(3):543-560.

California State Parks, 1998. Museum collections management handbook, volume I: basic references. Document on File, Museum Services Section, Park Services Division, Sacramento.

—— 2000. Museum collections management handbook, volume II: practices and procedures. Document on File, Museum Services Section, Park Services Division, Sacramento.

Campbell, K.E., E. Scott, Jr., and K.B. Springer, 1999. A new genus for the incredible teratorn (Aves: Teratornithidae). In Avian Paleontology at the Close of the 20th Century: Proceedings of the 4th International Meeting of the Society of Avian Paleontology and Evolution, Washington, D.C., edited by S.L. Olson, Smithsonian Contributions to Paleobiology 89:169-175.

Cassiliano, M.L., 1994. Paleoecology and taphonomy of vertebrate faunas from the Anza-Borrego Desert of California. Doctoral Dissertation, Department of Geosciences, University of Arizona, Tucson 421p.

—— 1997. Taphonomy of mammalian fossils across the Blancan-Irvingtonian boundary: Palm Spring Formation, Anza-Borrego desert of southern California. Palaeogeography, Palaeoclimatology, Palaeoecology 129:81-108.

—— 1998. Stable community structure of a terrestrial fauna in southern California across the Blancan-Irvingtonian boundary. Journal of Vertebrate Paleontology, Abstracts 18(3):32A.

—— 1999. Biostratigraphy of Blancan and Irvingtonian mammals in the Fish Creek section, southern California, and a review of the Blancan-Irvingtonian boundary. Journal of Vertebrate Paleontology 19(1)169-186.

Christensen, A.W., 1957. Part of the geology of the Coyote Mountain area, Imperial County, California. Master of Science Thesis, Department of Geology, University of California Los Angeles 188 p.

Coble, B.A., 1978. Intertidal environment in the Imperial Formation of southern California. Undergraduate Research Reports, Department of Geology, San Diego State University, California 33:16.

Conrad, T.A., 1854. Descriptions of new fossil shells of the United States. Journal of the Academy of Natural Sciences Philadelphia Series 2, 2(4):299-300.

—— 1855. Report on the fossil shells collected by W.P. Blake, geologist to the expedition under the command of Lieutenant R.S. Williamson, United States Topographical Engineers, 1852. In W.P. Blake, Preliminary Geological Report, U.S. Pacific Railroad Exploration, U.S. 33rd Congress, 1st session, House Executive Document 129:5-21, appendix.

Crouch, R.W., and C.W. Poag, 1979. Amphistegina gibbosa d'Orbigny from the California borderlands, the Caribbean connection. Journal of Foraminiferal Research 9(2):85-105.

Cunningham, G.D., 1984. The Plio-Pleistocene Dipodomyinae and geology of the Palm Spring Formation, Anza-Borrego Desert, California. Master of Science, Department of Geology, Idaho State University, Pocatello 193 p.

Dean, M.A., 1988. Genesis, mineralogy and stratigraphy of the Neogene Fish Creek gypsum, southwestern Salton Trough, California. Master of Science Thesis, San Diego State University, California 150 p.

—— 1996. Neogene Fish Creek gypsum and associated stratigraphy and paleontology, southwestern Salton Trough, California. In Sturzstroms and Detachment Faults Anza-Borrego Desert State Park California, edited by P. Abbott and D. Seymour, South Coast Geological Society Annual Field Trip Guide Book Number 24:123-148.

Deméré, T.A., 1993. Fossil mammals from the Imperial Formation (upper Miocene/lower Pliocene, Coyote Mountains, Imperial County, California. In Ashes, faults and basins, edited by R.E. Reynolds and J. Reynolds, San Bernardino County Museum Association Special Publication MDQRC 93(1):82-85.

Dibblee, T., 1954. Geology of the Imperial Valley region. In Geology of Southern California, edited by R.H. Jahns, California Division of Mines Bulletin 170:22-23.

Dickerson, R.E., 1918. Mollusca of the Carrizo Creek beds and their Caribbean affinities. Geological Society of America Special Paper 29:148.

Dockum, M.S. and R.H. Miller, 1982. Ordovician conodonts from the greenschist facies carbonates, western Imperial County, California. Geological Society of America Abstracts with Programs 14:160-161.

Douglas, A., 1971. Cenozoic marine faunas of the Imperial Formation of Whitewater and Fossil Canyon. Senior Thesis, Department of Geological Sciences, University of California, Riverside 24 p.

Dowlen, R.J., 1969. The coral-barnacle fauna of the Imperial Formation in Imperial County, California. Undergraduate Research Reports, Department of Geology, San Diego State University, California 14:1-34.

Downs, T., 1957. Late Cenozoic vertebrates from the Imperial Valley region, California. Geological Society of America Bulletin 68(12,2):1822.

—— 1965. Pleistocene vertebrates of the Colorado Desert, California. International Association for Quaternary Research, VII International Congress General Session, Abstracts with Programs p. 107.

—— 1966. Southern California field trip, Anza-Borrego Desert and Barstow areas. Society of Vertebrate Paleontology Field Trip, Manuscript on File Anza-Borrego Desert State Park, California 12 p.

—— 1967. Airlift for fossils. Los Angeles County Museum of Natural History Alliance Quarterly 6(1):20-25.

Downs, T. and G.J. Miller, 1994. Late Cenozoic equids from Anza-Borrego Desert, California. Natural History Museum of Los Angeles County Contributions in Science 440:1-90.

Downs, T., and J.A. White, 1965a. Late Cenozoic vertebrates of the Anza-Borrego Desert area, southern California. American Association for the Advancement of Science Meeting 1965:10-11.

—— 1965b. Pleistocene vertebrates of the Colorado Desert, California. International Association for Quaternary Research, VII International Congress, General Session Program p. 107.

—— 1966. The vertebrate faunal sequence of the Vallecito-Fish Creek area western Colorado Desert. In Southern California field trip, Anza-Borrego Desert and Barstow areas. Society of Vertebrate Paleontology Field Trip, Manuscript on File Anza-Borrego Desert State Park, California 5 p.

—— 1968. A vertebrate faunal succession in superposed sediments from late Pliocene to middle Pleistocene in California. In Tertiary/Quaternary Boundary, International Geological Congress 23, Prague 10:41-47.

Downs, T. and G.D. Woodard, 1961. Stratigraphic succession of the western Colorado Desert, San Diego and Imperial Counties, California. Geological Society of America Special Paper 68:73-74.

Durham, J.W., 1944. Lower California-Colorado Desert Area. In Correlation of the marine Cenozoic formations of western North America, chaired by C.E. Weaver, Bulletin of the Geological Society of America 55:574-575.

—— 1954. The marine Cenozoic of southern California. California Division of Mines Bulletin 170:23-31.

Durham, J.W. and E.C. Allison, 1961. Stratigraphic position of the Fish Creek gypsum at Split Mountain Gorge, Imperial County, California. Geological Society of America Special Paper 68:32.

Fairbanks, 1893. Geology of San Diego County, also portions of Orange and San Bernardino Counties. California State Mineral Bureau, 11th Annual Report of the State Mineralogist p. 88-90.

Fleming, R.F., 1993a. Palynological data from the Imperial and Palm Spring Formations, Anza-Borrego Desert State Park, California. U.S. Geological Survey Open-File Report 93-678:1-29.

—— 1993b. Cretaceous pollen and Pliocene climate. The American Association of Stratigraphic Palynologists, Program and Abstracts, Annual Meeting 26: 24.

—— 1994a. Cretaceous pollen in Pliocene rocks: implications for Pliocene climate in the southwestern United States. Geology 22:787-790.

Fleming, R.F., and P. Remeika, 1994. Pliocene climate of the Colorado Plateau and age of the Grand Canyon: evidence from Anza-Borrego Desert State Park, California. 4th NPS Conference on Fossil Resources, Colorado Springs, Colorado.

Foster, A.B., 1979. Environmental variation in a fossil scleractinian coral. Lethaia 12:245-264.

Fremd, T., 1995. Cyclic prospecting to preserve vertebrate paleontological resources. San Bernardino County Museum Quarterly 42(3):19-26.

Frick, C., 1921. Extinct vertebrate faunas of the badlands of Bautista Creek and San Timoteo Canyon, southern California. University of California Publications, Department of Geological Sciences Bulletin 12:277-409.

Grant, U.S., IV, and H.R. Gale, 1931. Pliocene and Pleistocene mollusca of California and adjacent regions. San Diego Society of Natural History Memoirs 1:1-1036.

Grant, U.S., IV, and L.G. Hertlein 1956. Schizaster morlini, a new species of echinoid from the Pliocene Imperial County, California. Southern California Academy of Sciences Bulletin 55:107-110.

Hanna, G.D., 1926. Paleontology of Coyote Mountain, Imperial County, California. Proceeding of the California Academy of Sciences, 4th Series, 14:427-503.

Hertlein, L.G. and E.K. Jordan, 1927. Paleontology of the Miocene of lower California. Proceedings of the California Academy of Sciences, 4th Series 16(19):607-611.

Howard, H., 1963. Fossil birds from the Anza-Borrego Desert. Los Angeles County Museum Contributions in Science 73:1-33.

—— 1972a. Type specimens of avian fossils in the collections of the Natural History Museum of Los Angeles County. Natural History Museum of Los Angeles County Contributions in Science 228:1-27.

——— 1972b. The incredible teratorn again. Condor 74(3):341-344.

Hutchison, J.H., 1987. Moles of the Scapanus latimanus group (Talpidae, Insectivora) from the Pliocene and Pleistocene of California. Natural History Museum of Los Angeles County Contributions in Science 386:1-15.

Ingle, J.C. Jr., 1974. Paleobathymetric history of Neogene marine sediments, northern Gulf of California. In Geology of Peninsular California, American Association of
Petroleum Geologists, Society of Economic Paleontologists and Mineralogists, Society of Exploration Geophysicists Pacific Sections Fieldtrip Guidebook p. 121-138.

Jass, C.N., 1998. Preliminary report on two new localities from the Truckhaven region, Anza-Borrego Desert State Park, CA. Journal of Vertebrate Paleontology, Abstracts 18(3):53A-54A.

Jefferson, G.T., 1966. The paleoecology of a "borrow horizon" in the base of the Imperial Formation at Whitewater, California. Manuscript on File Department of Geological Sciences, University of California, Riverside 13 p.

—— 1989. Late Cenozoic tapirs (Mammalia: Perissodactyla) of western North America. Natural History Museum of Los Angeles County Contributions in Science 406:1-21.

—— 1994. Paleontology, a view of the past. In Anza-Borrego Desert State Park Newspaper, 1995 Edition, edited by J. Quirk, Anza-Borrego Desert Natural History Association and the California State Park System, Borrego Springs p. 3.

—— 1995a. Digging in the badlands, the camel excavation. Tracks, Colorado Desert District Newsletter, May, Borrego Springs, California p.1-3., and In Anza-Borrego Desert State Park Newspaper, 1995 Edition, edited by J. Quirk, Anza-Borrego Desert Natural History Association and the California State Park System, Borrego Springs p. 3.

—— 1995b. An additional avian specimen referrable to Teratornis incrediblis from the early Irvingtonian, Vallecito-Fish Creek Basin, Anza-Borrego Desert State Park, California. In Paleontology and geology of the western Salton Trough Detachment, Anza-Borrego Desert State Park, California, edited by P. Remeika and A. Sturz, Field Trip Guidebook and volume for the 1995 San Diego Association of Geologist's field trip to Anza-Borrego Desert State Park, Volume 1:94-96.

—— 1996b. Paleontologic resources and collections management policy, Colorado Desert District. Document on File, State of California, Department of Parks and Recreation, Natural Heritage Division, Sacramento, and Colorado Desert District Stout Research Center, Borrego Springs 35 p.

—— 1999a. A late Miocene terrestrial vertebrate assemblage from Anza-Borrego Desert State Parkâ. In The 1999 Desert Research Symposium, edited by R.E. Reynolds, Abstracts of Papers Submitted to the Meetings, San Bernardino County Museum Association Quarterly 46(3):109-111.

—— 1999b. Anza-Borrego Desert State Parkâ 622 Paleontologic Resources Inventory and Management Recommendations. Document on File, State of California, Department of Parks and Recreation, Colorado District Stout Research Center, Borrego Springs 36 p.

Jefferson, G.T., R. Remeika, and L.K. Murray, 1995. Selected bibliography of the western Salton Trough detachment and related subjects, Anza-Borrego Desert
State Park, California. In Paleontology and geology of the western Salton Trough Detachment, Anza-Borrego Desert State Park, California, edited by P. Remeika and A. Sturz, Field Trip Guidebook and volume for the 1995 San Diego Association of Geologist's field trip to Anza-Borrego Desert State Park, Volume II:1-88.

Jefferson, G.T. and A. Tejada-Flores, 1995. Late Blancan Acinonyx (Carnivora, Felidae) from the Vallecito Creek Local Fauna of Anza-Borrego Desert State Park, California. Abstracts of Proceedings. 9th Annual Mojave Desert Quaternary Research Symposium, San Bernardino County Museum Quarterly 42(2):33.

Johnson, N.M., N.D. Opdyke, G.D. Woodard, P.K. Zeitler, and E.H. Lindsay, 1983. Rates of Cenozoic tectonism in the Vallecito-Fish Creek basin. Geology 11:664-667.

Jolly, D.W., 2000. Fossil turtles and tortoises of Anza-Borrego Desert State Parkâ, California. Master of Science Thesis, Quaternary Studies, Northern Arizona University 196 p.

Keen, M. and H. Bentson, 1944. Check list of California Tertiary marine mollusca. Geological Society of American Special Paper 56:21-22.

Kerr, D.R. and P.L. Abbott, 1996. Miocene suberial sturzstrom deposits, Split Mountain, Anza-Borrego Desert State Park. In Sturzstroms and Detachment Faults Anza-Borrego Desert State Park California, edited by P. Abbott and D. Seymour, South Coast Geological Society Annual Field Trip Guide Book Number 24:149-163.

Kerr, D.R., S. Pappajohn, and G.L. Peterson, 1979. Neogene stratigraphic section at Split Mountain, eastern San Diego County, California. In Tectonics of the Juncture Between the San Andreas Fault System and the Salton Trough, Southeastern California, edited by J.C. Crowell and A.G. Sylvester, Geological Society of America Annual Meeting Guidebook p. 111-124.

Kew, W.S.W., 1914. Tertiary echnoids of the Carrizo Creek region in the Colorado Desert. California University Publications, Bulletin of the Department of Geology 8:39-60.

—— 1920. Cretaceous and Cenozoic echinoidea of the Pacific coast of North America. University of California Publication of the Geology Department 12(2):32-137.

Kidwell, S.M., 1988. Taphonomic comparison of passive and active continental margins: Neogene shell beds of the Atlantic coastal plain and northern Gulf of California. Palaeogeography, Palaeoclimatology, Palaeoecology 63:201-223.

Kidwell, S.M., C.D. Winker, and E. D. Gyllenhaal, 1988. Transgressive stratigraphy of a marine rift basin: Neogene Imperial Formation, northern Gulf of California. Geological Society of America Abstracts with Programs 20:A380.

Lasby, R.L., 1969. The stratigraphy and paleontology of the Imperial Formation at Cabazon, California. Senior Thesis, Department of Geological Sciences, University of
California, Riverside 15 p.

Lindsay, E.H., N.M. Johnson, N.D. Opdyke, and R.F. Butler, 1987. Mammalian chronology and the magnetic time scale. In Cenozoic Mammals of North America, edited by M.O. Woodburne, University of California Press, Berkeley p. 212-235.

Lindsay et al., 1987. The North American Quaternary sequence. In Cenozoic Mammals of North America, Geochronology and Biostratigraphy, edited by M.O. Woodburne, University of California Press, Berkeley p. 269-290.

Lindsay, E.H. and J.S. White, 1993. Biostratigraphy and magnetostratigraphy in the southern Anza-Borrego area. In Ashes, Faults and Basins, edited by R. E. Reynolds and J. Reynolds, San Bernardino County Museum Association Special Publication 93-1:86-87.

Lundelius, E.L., Jr., T. Downs, E.H. Lindsay, H.A. Semken, R.J. Zakrzewski, C.S. Churcher, C.R. Harrington, G.E. Schultz, and S.D. Webb, 1987. The North American Quaternary sequence. In Cenozoic Mammals of North America, Geochronology and Biostratigraphy, edited by M.O. Woodburne, University of California Press, Berkeley p. 211-235.

Martin, R.A., 1993. Late Pliocene and Pleistocene cotton rats in the southwestern United States. In Ashes, faults and basins, edited by R.E. Reynolds and J. Reynolds, San Bernardino County Museum Association Special Publication 93(1):88-89.

Martin, R.A. and R.H. Prince, 1989. A new species of early Pleistocene cotton rat from the Anza-Borrego Desert of southern California. Southern California Academy of Sciences Bulletin 88(2):80-78.

McDaniel, G. and G.T. Jefferson, 1997. A Nearly Complete Skeleton of Mammuthus meridionalis from the Borrego Badlands, Anza-Borrego Desert State Park, California. In Memories, Minerals, Fossils, and Dust, edited by R.E. Reynolds and J. Reynolds, San Bernardino County Museum Association Quarterly 44(2):35-36.

—— 1999a. Distribution of proboscideans in Anza-Borrego Desert State Parkâ. In The 1999 Desert Research Symposium, edited by R.E. Reynolds, Abstracts of Papers Submitted to the Meetings, San Bernardino County Museum Association Quarterly 46(3):61-62.

——1999b. Mammuthus meridionalis (Proboscidea: Elephantidae) from the Borrego Badlands of Anza-Borrego Desert State Parkâ, California: phylogenetic and biochronologic implications. 2nd International Mammoth Conference, Rotterdam the Neatherlands, Abstracts p. 41-42.

——2001 (in press). Mammuthus meridionalis (Proboscidea: Elephantidae) from the Borrego Badlands of Anza-Borrego Desert State Park7, California: phylogenetic and biochronologic implications. 2nd International Mammoth Conference, Rotterdam the Netherlands, DEINSEA.

McDonald, H.G., G.T. Jefferson, and C. Force, 1996. Pleis tocene distribution of the ground sloth Nothrotheriops shastense (Xenarthra, Megalonychidae). The 1996 Desert Research Symposium, Abstracts of Papers Submitted to the Meetings, San Bernardino County Museum Association Quarterly 43(1,2):151-152.

McDougall, K., C.L. Powell, J.C. Matti, and R.Z. Poore, 1994. The Imperial Formation and the opening of the ancestral Gulf of California. Geological Society of America Abstracts with Programs 26(2):71.

Mendenhall, W.C., 1910. Notes on the geology of Carrizo Mountain, San Diego County, California. Journal of Geology 18(4):337-355.

Merriam, R.H., and O.L. Bandy, 1965. Source of upper Cenozoic sediments in the Colorado River delta region. Journal of Sedimentary Petrology 35:384-399.

Miller, G.J., 1977. A new cervid (Mammalia; Cervidae) from Anza-Borrego Desert, Imperial Valley, California. Manuscript on File, Colorado Desert District Stout Research Center, Anza-Borrego Desert State Parkâ, California 15 p.

—— 1980. A new subgenus and two new species of Odocoileus (Mammalia; Cervidae) with a study of variation in antlers. Manuscript on File, Colorado Desert District Stout Research Center, Anza-Borrego Desert State Parkâ, California 21 p.

—— 1985. A look into the past of the Anza-Borrego Desert. San Diego Natural History Museum Environment Southwest 510:12-17.

Miller, G.J., P. Remeika, J.D. Parks, B. Stout, and V.E. Waters, 1988. A preliminary report on half-a-million-year-old cutmarks on mammoth bones from the Anza-Borrego Desert Irvingtonian. Mojave Desert Quaternary Research Symposium, Abstracts of Proceedings, San Bernardino County Museum Association Quarterly 35(3-4):41.

—— 1989. A preliminary report on half-a-million-year-old cutmarks on mammoth bones from the Anza-Borrego Desert Irvingtonian. Symposium on the Value of the Desert, Anza-Borrego Desert Foundation, Borrego Springs, California, Abstracts p. 8.

—— 1991. A preliminary report on half-a-million year old cut marks on mammoth bones from the Anza-Borrego Desert Irvingtonian. Imperial Valley College Museum Society Occasional Paper 8:1-47.

Miller, G.J., B. Stout, and P. Remeika, 1982. Irvingtonian ichnites from the Anza-Borrego Desert, California. Society of Vertebrate Paleontology, Abstracts with Programs 42nd Annual Meeting, Mexico City.

Miller, R.H., and M.S. Dockum, 1983. Ordovician conodonts from metamorphosed carbonates of the Salton Trough, California. Geology 11:410-412.

Mitchell, E.D., Jr., 1961. A new walrus from the Imperial Pliocene of southern California: with notes on odobenid and otariid humeri. Los Angeles County Museum Contributions in Science 44:1-28.

Morgan, T.G., 1971. The paleoecology of the Willis Palms Formation oyster beds. Manuscript on File Department
of Geological Sciences, University of California, Riverside 11 p.

Mount, J.D., 1974. Molluscan evidence for the age of the Imperial Formation, southern California. Southern California Academy of Sciences Abstracts with Programs p. 9.

—— 1988. Molluscan fauna of the Imperial Formation. In Geologic Field Guide to the Western Salton Basin Area, edited by S.M. Testa and K.E. Green, American Institute of Professional Geologists p. 23-24.

Mueller, R.F., and K.C. Condie, 1964. Stability relations of carbon mineral assemblages in the southern California batholith. Journal of Geology 72:400-411.

Murphy, M.A., 1986. The Imperial Formation at Painted Hill, near Whitewater, California. In Geology Around the Margins of the Eastern San Bernardino Mountains, edited by M.A. Kooser and R.E. Reynolds, Inland Geological Society Publications, Redlands, California 1:63-70.

Murray, L.K., 1996. Curation manual for Anza-Borrego Desert State Parkâ and Colorado Desert District paleontological collections. Document on File, State of California, Department of Parks and Recreation, Colorado Desert District Stout Research Center, Borrego Springs 54 p.

Murray, L.K. and G.T. Jefferson, 1996. A review of the Procyonids (Carnivora) from the late Blancan and early Irvingtonian Vallecito Creek Local Fauna of Anza-Borrego Desert State Park, California. Abstracts of Proceedings, 10th Annual Mojave Desert Quaternary Research Symposium, San Bernardino County Museum Association Quarterly 43(1,2):153.

National Park Service, 1977. Paleontological resources management. Natural Resources Management Guideline, National Park Service NPS-77(2):155-175.

Norell, M.A., 1989. Late Cenozoic lizards of the Anza-Borrego Desert, California. Natural History Museum of Los Angeles County Contributions in Science 414:1-31.

Opdyke, N.D., E.H. Lindsay, N.M. Johnson, and T. Downs, 1974. The magnetic polarity stratigraphy of the mammal bearing sedimentary sequence at Anza-Borrego State Park, California. Geological Society of America Abstracts with Programs 6:901.

—— 1977. The paleomagnetism and magnetic polarity stratigraphy of the mammal-bearing section of Anza-Borrego State Park, California. Quaternary Research 7(3):316-329.

Pappajohn, S., 1980. Description of Neogene marine section at Split Mountain, easternmost San Diego County, California. Master of Science Thesis, San Diego State University 72 p.

Parks, J., B. Stout, G.J. Miller, P. Remeika, and V.E. Waters, 1989. A progress report on half-million year old marks on mammoth bones from the Anza-Borrego Desert Irvingtonian. Mojave Desert Quaternary Research Symposium, Abstracts of Proceedings, San Bernardino County Museum Association Quarterly 36(2):63.

Powell, C.L., II, 1984. Review of the marine Neogene Imperial Formation, southern California. Society of Economic Paleontologists and Mineralogists, Pacific Section p. 29.

—— 1986. Stratigraphy and bivalve molluscan paleontology of the Neogene Imperial Formation in Riverside County, California. Master of Science Thesis, California State University, San Jose 275 p.

—— 1987. Paleogeography of the Imperial Formation of southern California and its molluscan fauna: an overview. Western Society of Malacologists Annual Report 20:11-18.

—— 1995. Preliminary report on the Echinodermata of the Miocene and Pliocene Imperial Formation in southern California. In Paleontology and geology of the western Salton Trough Detachment, Anza-Borrego Desert State Park, California, edited by P. Remeika and A. Sturz, Field Trip Guidebook and Volume for the 1995 San Diego Association of Geologist's Field Trip to Anza-Borrego Desert State Park, Volume 1:55-63.

Quinn, H.A., and T.M. Cronin, 1984. Micro-paleontology and depositional environments of the Imperial and Palm Spring Formations, Imperial Valley, California. In The Imperial Basin, Tectonics, Sedimentation and Thermal Aspects, edited by C.A. Rigsby, Society of Economic Paleontologists and Mineralogists 40:71-85.

Remeika, P., 1988. Lower Pliocene petrified wood from the Palm Spring Formation, Anza-Borrego Desert State Park, California. Review of Palaeobotany and Palynology 56:183-198.

—— 1991. Formational status of the Diablo Redbeds; differentiation between Colorado River affinities and the Palm Spring Formation. Symposium on the Scientific Value of the Desert, Anza-Borrego Foundation, Borrego Springs, California, Abstracts p. 12.

—— 1992a. Anza-Borrego Desert State Park Paleontology Collection Management Policy. California Department of Parks and Recreation, Anza-Borrego Desert State Park 47 p.

—— 1992b. Preliminary report on the stratigraphy and vertebrate fauna of the middle Pleistocene Ocotillo formation, Borrego Badlands, Anza-Borrego Desert State Park, California. Mojave Desert Quaternary Research Symposium, Abstracts of Proceedings, San Bernardino County Museum Association Quarterly 39(2):25-26.

—— 1994. Lower Pliocene angiosperm hardwoods from the Vallecito-Fish Creek Basin, Anza-Borrego Desert State Park, California: deltaic stratigraphy, paleoclimate, paleoenvironment, and phytogeographic significance. Abstracts of Proceedings. 8th Annual Mojave Desert Quaternary Research Center Symposium. San Bernardino County Museum Association Quarterly 41(3):26-27.

—— 1995. Basin tectonics, stratigraphy, and depositional environments of the western Salton Trough detachment: the 1995 San Diego Association of Geologist's Field Trip Guide to Anza-Borrego Desert State Park, California. In Paleontology and geology of the western Salton Trough Detachment, Anza-Borrego Desert State Park,
California, edited by P. Remeika and A. Sturz, Field Trip Guidebook and volume for the 1995 San Diego Association of Geologist's field trip to Anza-Borrego Desert State Park, Volume 1:3-54.

—— 1997a. Neogene Vallecito-Fish Creek Basin: tilt-block/half graben extension, stratigraphy, and paleontology. In Geology and Paleontology of the Anza-Borrego Region, California, edited by P. Dean, C. Metzler, and A. Trujillo, National Association of Geology Teachers, Far Western Section, Spring Conference Field Guide, Field Trip I 32 p.

—— 1997b. Roadside basin-margin outcrop geology of the Borrego Badlands: an overview. In Geology and Paleontology of the AnzaBorrego Region, Califonia, edited by P. Dean, C. Metzler, and A. Trujillo, National Association of Geology Teachers, Far Western Section, Spring Conference Field Guide, Field Trip IV 20 p.

—— 1998a. Interdisciplinary age control of the western Borrego Badlands, Anza-Borrego Desert State Park, California. National Park Service, Abstracts for the Fifth Fossil Conference, Rapid City, South Dakota, p.18.

—— 1998b. Marine invertebrate paleontology and stratigraphy of the Vallecito-Fish Creek Basin: a historic review, synthesis, and revision. In Geology and Hydrothermal Resources of the Imperial and Mexicali Valleys, edited by L. Lindsay and W.G. Hample, San Diego Association of Geologists Annual Field Trip Guidebook 1998 pp. 59-92.

Remeika, P., and S. Beske-Dehl, 1996. Magnetostratigraphy of the western Borrego Badlands, Anza-Borrego Desert State Park, California: implications for stratigraphic age control. In Geology of Neogene Faulting and Catastrophic Events in the Split Mountain Area, Anza-Borrego Desert State Park, California, edited by D. Seymour and P.L. Abbott, South Coast Geological Society Field Trip Guidebook 24:209-220.

Remeika, P., I.W. Fischbein, and S.A. Fischbein, 1986. Lower Pliocene petrified wood from the Palm Spring Formation, Anza-Borrego Desert State Park, California. In Geology of the Imperial Valley, California, edited by P.D. Guptil, E.M. Gath, and R.W. Ruff, South Coast Geological Society, Annual Field Trip Guidebook, Santa Ana, California 14:65-83.

Remeika, P., and R.F. Fleming, 1994. Pliocene climate of the Colorado Plateau and age of the Grand Canyon: evidence from Anza-Borrego Desert State Park, California. In Partners in Paleontology - - Proceedings of the Fourth Conference on Fossil Resources, edited by M. Johnson and J. McChristal, U.S. Department of the Interior Natural Resources Report NPS/NRFLFO/NRR-97/01 p. 17.

—— 1995. Cretaceous palynoflora and Neogene angiosperm woods from Anza-Borrego Desert State Park, California: implications for Pliocene climate of the Colorado Plateau and age of the Grand Canyon. In Paleontology and geology of the western Salton Trough Detachment, Anza-Borrego Desert State Park, California, edited by P. Remeika and A. Sturz, Field Trip Guidebook and volume for the 1995 San Diego Association of Geologist's field trip to Anza-Borrego Desert State Park, Volume 1:64-81.

Remeika, P., and G.T. Jefferson, 1993. The Borrego Local Fauna: revised basin-margin stratigraphy and paleontology of the western Borrego Badlands, Anza-Borrego Desert State Park, California. In Ashes, Faults and Basins, edited by R.E. Reynolds and J. Reynolds. San Bernardino County Museum Association Special Publication 93(1):90-93.

Remeika, P., G.T. Jefferson, and L.K. Murray, 1995. Fossil vertebrate faunal list for the Vallecito-Fish Creek and Borrego-San Felipe Basins, Anza-Borrego Desert State Park and vicinity, California. In Paleontology and geology of the western Salton Trough Detachment, Anza-Borrego Desert State Park, California, edited by P. Remeika and A. Sturz, Field Trip Guidebook and volume for the 1995 San Diego Association of Geologist's field trip to Anza-Borrego Desert State Park, Volume 1:82-93.

Richardson, S.M., 1984. Stratigraphy and depositional environments of a marine-nonmarine Plio-Pleistocene sequence, western Salton Trough, California. Master of Science Thesis, San Diego State University, California 112 p.

Rymer, M.J., 1991. The Bishop ash bed in the Mecca Hills. In Geological excursions in southern California and Mexico, edited by M.J. Walawender and B.B. Hanan, Guidebook, 1991 Annual Meeting, Geological Society of America, San Diego State University, California p.388-396.

Schaeffer, G.C., 1857. Description of the structure of fossil wood from the Colorado Desert. In 1855 Report of the Explorations and Survey for a Railroad Route from the Mississippi to the Pacific, U.S. Congress, 2nd Session, Senate Executive Document 91, 5(2):338-339.

Schremp, L.A., 1981. Archaeogastropoda from the Pliocene Imperial Formation of California. Journal of Paleontology 55(5):1123-1136.

Stewart, J.D., and M. Roeder, 1993. Razorback sucker (Xyrauchen) fossils from the Anza-Borrego Desert and the ancestral Colorado River. In Ashes Faults and Basins, edited by R.E. Reynolds and J. Reynolds, San Bernardino County Museum Special Publication 93(1):94-96.

Stout, B.W., and P. Remeika, 1991. Status report on three major camel track sites in the lower Pliocene delta sequence, Vallecito-Fish Creek Basin, Anza-Borrego Desert State Park, California. Symposium on the Scientific Value of the Desert, Anza-Borrego Foundation, Borrego Springs, California p. 9.

Stump, T.E., 1970. Stratigraphy and paleoecology of the Imperial Formation in the western Colorado Desert. Undergraduate Research Reports, Department of Geology, San Diego State University, California 16(2):1-118.

—— 1972. Stratigraphy and paleoecology of the Imperial Formation in the western Colorado Desert. Master of
Science Thesis, San Diego State University, California 128 pp.

Stump, T.E., and J.D. Stump, 1972. Age, stratigraphy, paleoecology and Caribbean affinities of the Imperial fauna of the Gulf of California depression. Geological Society of America Special Paper 4(3):243.

Taylor, D.W., 1966. Summary of North American Blancan nonmarine molluscs. Malacologica 4:1-172.

Tarbet, L.A., and W.H. Holman, 1944. Stratigraphy and micropaleontology of the west side of Imperial Valley. American Association of Petroleum Geologists Bulletin 28:1781-1782.

Thomas, H.W., and L.G. Barnes, 1993. Discoveries of fossil whales in the Imperial Formation, Riverside County, California: possible further evidence of the northern extent of the proto-Gulf of California. In Ashes, Faults and Basins, edited by R.E. Reynolds and J. Reynolds, San Bernardino County Museum Association Special Publication 93(1):34-36.

Tucker, A.B., R.M. Feldman, and C.L. Powell, II, 1994. Speocarcinus berglundi n. sp. (Decapoda: Brachyura), a new crab from the Imperial Formation (late Miocene-late Pliocene) of southern California. Journal of Paleontology 68(4):800-807.

Vaughan, T.W., 1904. A California Tertiary coral reef and its bearing on American Recent coral faunas. Science (new series) 19:503.

—— 1917a. The reef-coral fauna of Carrizo Creek, Imperial County, California and its significance. U.S. Geological Survey Professional Paper 98T:355-387.

—— 1917b. Significance of reef coral fauna at Carrizo Creek, Imperial Co., Calif. Washington Academy of Science Journal 7:194.

Watkins, R., 1990a. Pliocene channel deposits of oyster shells in the Salton Trough region, California. Palaeogeography, Palaeoclimatology, Palaeoecology 79:249-262.

—— 1990b. Paleoecology of a Pliocene rocky shoreline, Salton Trough region, California. Palaios 5:167-175.

Webb, S.D., 1998. Chronology and ecology of vertebrates: who went when. American Quaternary Association. Program and Abstracts of the 15th Biennial Meeting p. 66-68.

Webb, S.D. and A.D. Barnosky, 1989. Faunal dynamics of Pleistocene mammals. Annual Review of Earth and Planetary Sciences 17:413-438.

White, J.A., 1964. Kangaroo rats (Family Heteromyidae) of the Vallecito Creek Pleistocene of California. Geological Society of America Special Paper 82:288-289.

—— 1965. Late Cenozoic vertebrates of the Anza-Borrego Desert area, southern California. American Association for the Advancement of Science, Abstracts with Program, Berkeley, California.

—— 1968. A new porcupine from the middle Pleistocene of the Anza-Borrego Desert of California. Los Angeles County Museum of Natural History Contributions in Science 136:1-15.


—— 1969. Late Cenozoic bats (Subfamily Nyctophylinae) from the Anza-Borrego Desert of California. University of Kansas Museum of Natural History Miscellaneous Publications 51:275-282.

—— 1970. Late Cenozoic porcupines (Mammalia, Erethizontidae) of North America. American Museum Novitates 241:1-15.

—— 1984. Late Cenozoic Leporidae (Mammalia, Lagomorpha) from the Anza-Borrego Desert, southern California. Special Publication of the Carnegie Museum of Natural History 9:41-57.

—— 1991. North American Leporinae (Mammalia: Lagomorpha) from late Miocene (Clarendonian) to latest Pliocene (Blancan). Journal of Vertebrate Paleontology 11(1):67-89.

White, J.A. and T. Downs, 1961. A new Geomys from the Vallecito Creek Pleistocene of California. Los Angeles County Museum Contributions in Science 42:1-34.

—— 1965. Pleistocene vertebrates of the Colorado Desert, California. Abstract in Program, Association of Quaternary Research, VII International Congress, Denver, Colorado p. 107.

Wylie, J., 1991. The effects of wilderness designation on cultural resources. Manuscript on File, State of California, Department of Parks and Recreation, Colorado Desert District Stout Research Center, Borrego Springs 6 p.

Winker, C.D., 1987. Neogene stratigraphy of the Fish Creek-Vallecito section, southern California: implications for early history of the northern Gulf of California and Colorado delta. Doctoral Dissertation, University of Arizona, Tucson 494 p.

Winker, C.D. and S.M. Kidwell, 1996. Stratigraphy of a marine rift basin: Neogene of the western Salton Trough, California. In Field Conference Guide, edited by P.L. Abbott and J.D. Cooper, Pacific Section of American Association of Petroleum Geologists, GB 73, Pacific Section Society of Economic Paleontologists and Mineralogists, Book 80 p. 295-336.

Woodard, G.D., 1963. The Cenozoic succession of the west Colorado Desert, San Diego and Imperial Counties, southern California. Doctoral Dissertation, University of California, Berkeley 173 p.

—— 1974. Redefinition of Cenozoic stratigraphic column in Split Mountain Gorge, Imperial Valley, California. American Association of Petroleum Geologists Bulletin 58:521-539.

Woodring, W.P., 1931. A Miocene Haliotis from southern California. Journal of Paleontology 5:34-39.

Zakrzewski, R.J., 1972. Fossil microtines from late Cenozoic deposits in the Anza-Borrego Desert, California, with a description of a new subgenus of Synaptomys. Los Angeles County Museum of Natural History Contributions in Science 221:1-12.